Examine this patient's visual fields.
· Sudden onset usually.
· Patient notices a 'hole' in the vision while reading a poster or looking at a clock.
· Central scotoma (allow the patient to find the defect himself by moving the white hat pin in his own visual field). Then
1. The size and shape of the defect by moving the pin in and out of the blind area.
2. Whether the defect crosses the horizontal midline (vascular defects of retina do not do so).
3. Whether the defect crosses the vertical midline (defects due to pathway damage have a sharp vertical edge at the
4. Whether the defect extends to the blind spot- so-called 'caecocentral scotoma' (seen in glaucoma, vitamin Bi2 deficiency).
5. Whether there is a similar defect in the other eye (to exclude homonymous hemianopic scotomas).
· Examine the fundus. Remember that the optic discs may be:
-Pale (optic atrophy).
- Normal (retrobulbar neuritis).
- Swollen and pink (papillitis).
This patient has a central scotoma (lesion) due to optic atrophy (aetiology).
What do you understand by the term 'scotoma'?
It is a small patch of visual loss within the visual field.
Mention a few underlying causes for central scotoma.
· Demyelinating disorders (multiple sclerosis).
· Optic nerve compression by tumour, aneurysm.
· Toxins methanol, tobacco, lead, arsenical poisoning.
· Ischaemia - including central retinal artery occlusion due to thromboembolism, temporal arteritis, syphilis, idiopathic acute
· Hereditary disorders - Friedreich's ataxia, Leber's optic atrophy.
· Paget's disease.
· Vitamin B12 deficiency.
· Secondary to retinitis pigmentosa.